[area-stacked] Stacked Area Chart

[MarkusNeusinger]

Plot Request

Multiple areas stacked showing cumulative total.

Use Cases

• Revenue by product over time
• Traffic sources over time
• Resource allocation

Expected Features

• Areas stacked on top of each other
• Different colors per series
• Legend identifying series

[claude]

✅ Spec ID: area-stacked

Rationale: Stacked area charts are a distinct variant from basic area charts, showing multiple series stacked to display cumulative totals over a continuous axis.

This is not a duplicate - area-basic covers single-series area charts, while this request specifically targets the stacked variant with multiple colored series.

[github-actions]

✅ Specification Ready: area-stacked

PR: #2036

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specification.md

area-stacked: Stacked Area Chart

Description

A stacked area chart displays multiple data series as areas stacked on top of each other, with each series starting where the previous one ends. This visualization emphasizes both individual contributions and cumulative totals over a continuous axis (typically time). It is ideal for showing how parts contribute to a whole while tracking changes over time, making patterns of composition and overall trends immediately visible.

Applications

• Revenue breakdown by product line over time
• Website traffic sources (direct, organic, referral, social) over months
• Resource allocation across departments or projects
• Energy consumption by sector over years

Data

• x (datetime/numeric) - continuous axis values, typically time periods
• y1, y2, y3, ... (numeric) - values for each series to be stacked
• category (categorical) - labels identifying each series
• Size: 10-100 time points, 2-8 series
• Example: monthly revenue by product category over two years

Notes

• Use distinct but harmonious colors for each series
• Order series by size (largest at bottom) for easier reading
• Include legend to identify each series
• Consider using semi-transparent fills for overlapping visibility
• Ensure baseline starts at zero to avoid misleading proportions

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Next: Add approved label to merge this specification to main.

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